Brocade FastIron Ethernet Switch Administration Guide - Manual (Page 61)

mode changing, it is recommended that you first change to auto mode on one side, before switching
to another force mode configuration.
Enabling auto-negotiation maximum port speed advertisement and
down-shift
NOTE
For optimal link operation, link ports on devices that do not support 802.3u must be configured with like
parameters, such as speed (10,100,1000), duplex (half, full), MDI/MDIX, and Flow Control.
Maximum Port speed advertisement is an enhancement to the auto-negotiation feature, a mechanism
for accommodating multi-speed network devices by automatically configuring the highest performance
mode of inter-operation between two connected devices.
Port speed down-shift enables Gbps copper ports on the Brocade device to establish a link at 1000.
Mbps over a 4-pair wire when possible, or to down-shift to 100 Mbps if the medium is a 2-pair wire.
Maximum port speed advertisement enables you to configure an auto-negotiation maximum speed that
Gbps copper ports on the Brocade device will advertise to the connected device. You can configure a
port to advertise a maximum speed of either 100 Mbps or 10 Mbps. When the maximum port speed
advertisement feature is configured on a port that is operating at 100 Mbps maximum speed, the port
will advertise 10/100 Mbps capability to the connected device. Similarly, if a port is configured at 10
Mbps maximum speed, the port will advertise 10 Mbps capability to the connected device.
The maximum port speed and down-shift advertisement features operate dynamically at the physical
link layer between two connected network devices. They examine the cabling conditions and the
physical capabilities of the remote link, then configure the speed of the link segment according to the
highest physical-layer technology that both devices can accommodate.
The maximum port speed and down-shift advertisement features operate independently of logical trunk
group configurations. Although Brocade recommends that you use the same cable types and auto-
negotiation configuration on all members of a trunk group, you could utilize the auto-negotiation features
conducive to your cabling environment. For example, in certain circumstances, you could configure
each port in a trunk group to have its own auto-negotiation maximum port speed advertisement or port
speed down-shift configuration.
Maximum port speed advertisement and down-shift application notes
• The maximum port speed advertisement works only when auto-negotiation is enabled (CLI command
speed-duplex auto ). If auto-negotiation is OFF, the device will reject the maximum port speed
advertisement configuration.
• When the maximum port speed advertisement is enabled on a port, the device will reject any
configuration attempts to set the port to a forced speed mode (100 Mbps or 1000 Mbps).
• When port speed down-shift or maximum port speed advertisement is enabled on a port, the device
will reject any configuration attempts to set the port to a forced speed mode (100 Mbps or 1000
Mbps).
Configuring maximum port speed advertisement
NOTE
This is not supported in ICX devices.
Enabling auto-negotiation maximum port speed advertisement and down-shift
FastIron Ethernet Switch Administration Guide 61
53-1003075-02